Effect Of Combined Application Of Reducing Nitroge N And Organic Fertilizer On Soil Chemical Properties And Nitrogen Utilization Of Maize In Central Sichuan Hilly Area

In agricultural production,the use of nitrogen fertilizers has increased dramatically.Although the production has increased,it has also caused a severe decline in soil fertility,a decline in the quality of agricultural products,and environmental pollution.Therefore,it is necessary to reduce the use of chemical fertilizers and increase the efficiency of fertilizer nutrient use.The combined application of organic fertilizers and inorganic fertilizers can not only improve the chemical properties of soil,improve the structure of the soil,but also ensure the high and stable yield of crops,as well as improve the efficiency of fertilizer use,thus avoiding environmental pollution.Organic manure instead of chemical fertilizers and comprehensive and rational application of fertilizer resources are the main ways to reduce the zero-growth target of China’s chemical fertilizer application.In this paper,field experiments were conducted to set up a two-factor test of nitrogen application rate and organic fertilizer,using blank treatment（CK₀）and conventional nitrogen application（CK₁）as controls.The factor A was the amount of nitrogen fertilizer（nitrogen reduction 20%A₁and nitrogen reduction 40%A₂）.The factor B was the amount of organic fertilizer（without organic fertilizer B₀,organic fertilizer B₁,biological organic fertilizer B₂）.It studied the effects of reducing nitrogen fertilization with organic manure on soil chemical properties and nitrogen utilization in maize in the hills of central Sichuan.The main results are as follows:1.The nitrogen reduction combined with organic fertilizer significantly increased the plant height and stem diameter of corn.At the late growth stage of maize,the leaf area index and chlorophyll content in the panicle leaf decreased with the decrease of nitrogen application rate.Combined application of organic fertilizer can delay leaf senescence,increase leaf area index,chlorophyll content,and increase plant photosynthetic capacity at the later stage of maize growth..Reducing 20%nitrogen with organic fertilizer can delay leaf senescence,increase photosynthetic capacity and enhance photosynthesis potential.2.Different fertilization treatments increased soil available nutrient content,enzyme activity and carbon pool management index.For two years,its performance was A₁B₂>A₁B₁>CK₁>A₁B₀>A₂B₂>A₂B₁>A₂B₀>CK₀.With the decrease of nitrogen application rate,soil nutrient content,soil enzyme activity,and carbon pool management index gradually decreased.The application of organic fertilizer significantly improved soil chemical properties.In the case of 20%nitrogen reduction with organic fertilizer,compared with A₁B₀,the urease activity of A1B1 and A₁B₂ increased by 28.90%and32.87%,respectively;the alkaline nitrogen at the silking stage increased by 9.48 mg/kg and 10.49 mg/kg,respectively;the alkaline nitrogen at maturity increased by an average of11.56 mg/kg and 12.94 mg/kg;TOC increased by an average of 19.29 and 37.26%;CPMI increased by an average of 27.73%and 38.58%.Appropriate reduction of 20%nitrogen fertilizer with organic fertilizer can improve soil available nutrient content,enzyme activity,carbon stock index,and improve soil fertility.3.With the decrease of nitrogen fertilizer application,dry matter accumulation and nitrogen accumulation of maize gradually decreased.The application of organic fertilizer significantly increased the accumulation of dry matter and the accumulation of nitrogen in corn,and significantly increased the amount of material accumulation and distribution of reproductive organs during the later reproductive period,and reduced the amount of material accumulation and distribution ratio of vegetative organs.Under the condition of20%reduction of nitrogen and application of organic fertilizer,the dry matter accumulation of A₁B₁ and A₁B₂ increased by 31.38%and 46.10%on average compared with A₁B₀;the accumulation of corn nitrogen increased by an average of 44.46%and65.67%.In the case of 20%nitrogen reduction with organic fertilizer,the amount of translocation before flowering and post-anthesis accumulation were higher than those of other fertilization treatments,making the comprehensive utilization of maize nitrogen higher than that of other fertilization treatments.4.The overall trend of corn yield was A₁B₂>A₁B₁>CK₁>A₁B₀>A₂B₂>A₂B₁>A₂B₀>CK₀.With the reduction of nitrogen application,the yield and economic benefits are reduced.The yield of maize of A₁B₂ was 812.41kg/hm² higher than that of CK₁,The economic benefit of A₁B₂ was 7.34%higher than that of CK₁.Nitrogen reduction of 20%with organic fertilizer significantly improved corn ear traits and increased maize yield.Compared with A₁B₀,A₁B₂ and A₁B₁ corn yields increased by an average of 23.76%and17.33%;100-grain weight increased by 7.98%and 5.45%;economic benefits increased by12.42%and 20.27%.Appropriately reducing the amount of nitrogen fertilizer applied with organic fertilizer can significantly improve the ear traits and yield of corn.Nitrogen reduction of 20%with bio-organic fertilizer resulted in slower leaf senescence,stronger photosynthetic characteristics,and higher dry matter accumulation,thereby increasing corn yield.With the reduction of the amount of nitrogen fertilizer application,the yield per unit area of corn decreased,and the application of organic fertilizer can increase the yield per unit area of corn.